feat: allow attaching to paths inside archives

[stephank]

This change allows attaching to buffers with zipfile: or tarfile: virtual paths.

A function util.strip_archive_subpath(path) was added to extract the archive path from such a virtual path, and root_dir for tsserver is configured to use it by default. This means the root_dir search for TypeScript starts at the archive, instead of doing a real traversal starting from the file inside the archive. This is a compromise, because otherwise we'd have to provide a whole bunch of support functionality (currently provided by vim.loop) to do the necessary checks inside archives.

I targeted TypeScript for Yarn PnP support, which keeps project dependencies in zip files instead of node_modules. I imagine this may also be useful for other languages, like Java with JARs, but I'm really not familiar with those.

An alternative solution I considered was to add behaviour like strip_archive_subpath to existing utility functions to accomplish the same, but I'm worried about breaking existing code, and perhaps other language servers need different behaviour.

[rafaeldelboni]

Thanks for this PR, it will probably help clojure-lsp as well since we do have zipfiles and jar:files buffer types

[justinmk]

Not sure I fully understand. Is the point to trick the root finder into thinking that this file exists on the project path? Then this should be handled in the root finder, instead of special-casing a bunch of lspconfigs. And we definitely would want a few test cases like:

assert('...' == fixup_filepath('zipfile://...')
assert('...' == fixup_filepath('tarfile://...')
...

[stephank]

I rebased and added tests, plus removed the special casing.

The idea is to have the root finder start the search at the zipfile itself, for a buffer with a file inside a zipfile. I have a Yarn v3 project and when I jump to the definition of a dependency, it looks like:

zipfile:///path/to/project/.yarn/cache/some-dependency-1.2.3-abcde456.zip::node_modules/some-dependency/index.js

By starting the lookup at some-dependency-1.2.3-abcde456.zip, it can eventually find /path/to/project as the root and use the same tsserver as the rest of the project.

[glepnir]

LGTM